The invention is based on a fuel injection system as defined hereinafter. From German Offenlegungsschrift No. 31 02 853, a fuel injection system is already known in which the fuel flowing via a fuel supply line to the injection valve and the excess fuel carried away from the injection valve via a fuel return line partly flushes the valve housing, for the sake of improved cooling.
In hot starting of an internal combustion engine equipped with this type of injection valve, the formation of fuel vapor bubbles can cause difficulties in starting particularly if fuel that includes vapor bubbles is ejected in the first few seconds after starting. These difficulties are due to the severe leaning down of the thereby formed fuel-air mixture and its attendant poor ignition performance.